The objective of this research is to evaluate the decrease in cancer risk resulting in the removal of plutonium and other actinide elements from the body by chelation therapy. We are observing 17 beagles injected with Pu-239 or Am-241 during 1973-1976, and then given protracted therapy with zinc-DTPA or calcium-DTPA. This therapy has decreased the skeletal burdens by an average factor of 5. It is possible that many of these dogs will lead normal lives free of radionuclide-induced cancer. As of March 1981, two dogs have died; one with an osteosarcoma and the other from causes apparently unrelated to irradiation. Without the DTPA therapy, bone cancers should now have appeared in about 13 of these 17 beagles. We have injected 504 mice with Pu-239. Some are untreated, while others are receiving zinc-DTPA therapy for either 2 weeks, 2 months or 1 year. The purpose is to compare the effectiveness of brief vs. protracted chelation therapy in decreasing the risk from plutonium-induced cancer. In collaboration with Drs. P. W. Durbin, K. N. Raymond, and F. L. Weitl at Berkeley, we are testing in beagles the effectiveness and safety of new chelating agents, such as LICAM-C, that, hopefully, may be superior to DTPA.